Ikanogavialis
Ikanogavialis is an extinct genus of gryposuchine gavialoid crocodilian. Fossils have been found from the Urumaco Formation of Venezuela. The strata from which remains are found are late Miocene in age, rather than Pliocene as was once thoughtLangston, W. and Gasparini, Z. (1997). Crocodilians, Gryposuchus, and the South American gavials. In: Kay, R. F., Madden, R. H., Cifelli, R. L. and Flynn, J. J., eds., Vertebrate Paleontology in the Neotropics: The Miocene fauna of La Venta, Colombia. Washington, D.C. Smithsonian Institution Press, pp. 113-154.. Description Ikanogavialis had a dorsoventrally deep snout and a distinctive notch between the dentary and maxillary alveoli Sill, W. D. (1970). Nota preliminar sobre un nuevo gavial del Plioceno de Venezuela y una discusion de los gaviales sudamericanos. Ameghiniana 7':151–159.. The external nares projected anterodorsally from the rostrum. This can be seen as a plesiomorphic characteristic in crocodilians, but given that the earliest gavialoids possessed dorsally projecting external nares, this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor. Species The type species of ''Ikanogavialis is I. gameroi. It was named in 1970 from material found from the Urumaco Formation. A Pleistocene gavialid found from Murua, part of the Solomon Islands, may be a new species of Ikanogavialis. Named Gavialis papuensis in 1905, it was at first thought to be a species of gharial on the basis of its long, narrow snout. It was later shown to be a closer relative of the extinct crocodilians Charactosuchus, Euthecodon and Ikanogavialis in 1982, which all bear deep interalveolar notchesMolnar, R. E. (1982). A longirostrine crocodilian from Murua (Woodlark), Solomon Sea. Memoirs of the Queensland Museum '''20:675-685.Brochu, C. A. and Rincon, A. D. (2004). A gavialoid crocodylian from the Lower Miocene of Venezuela. Special Papers in Palaeontology 71:61-78.At the time it was not known that Charactosuchus and Ikanogavialis were both longirostrine crocodiles and thus unrelated to Ikanogavialis.. Because of the close similarities with Ikanogavialis in particular, it was considered synonymous with the genus in 1999Rauhe, M., Frey, E., Pemberton, D. S., and Rossmann, T. (1999). Fossil crocodilians from the Late Miocene Baynunah Formation of the Emirate of Abu Dhabi, United Arab Emirates: osteology and palaeoecology. In: Whybrow, P. J. and Hill, A., eds., Fossil vertebrates of Arabia New Haven. Yale University Press, pp. 163–185.. Paleobiology Ikanogavialis may have lived in a coastal paleoenvironment along with other gavialids such as Gryposuchus. The strata of the Urumaco Formation were deposited in both marine and fluvial settings, although it is unclear to which portion both genera belongLinares, O. J. (2004). Bioestratigrafia de la fauna de mamiferos de las Formaciones Socorro, Urumaco y Codore (Mioceno Medio–Plioceno Temprano) de la region de Urumaco, Falcon, Venezuela. Paleobiologia Neotropical 1':1–26.Sánchez-Villagra, M. R. and Aguilera, O. A. (2006). Neogene vertebrates from Urumaco, Falcón State, Venezuela: diversity and significance. ''Journal of Systematic Palaeontology '''4:213–220.. Other gavialoids such as Siquisiquesuchus and Piscogavialis are known to have lived in coastal environments, and it is likely that extant freshwater gavialoids such as Gavialis may have originated from these coastal formsKraus, R. (1998). The cranium of Piscogavialis jugaliperforatus n. gen., n. sp. (Gavialidae, Crocodylia) from the Miocene of Peru. Paläontologische Zeitschrift 72:389–406.Brochu C. A. and Rincon, A. D. (2004). A gavialoid crocodylian from the Lower Miocene of Venezuela. Special Papers in Palaeontology 71:61–78.. Ikanogavialis also existed with many other crocodilians in Venezuela during the late Miocene including the giant caiman Purussaurus and an extinct species of Melanosuchus''Aguilera, O. A., Driff, D. and Bocquentin-Villanueva, J. (2006). A new giant Purussaurus (Crocodyliformes, Alligatoridae) from the Upper Miocene Urumaco Formation, Venezuela. ''Journal of Systematic Paleontology 4(3):221-232.. Notes and references External links *[http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=38418&is_real_user=1 Ikanogavialis] in the Paleobiology Database Category:Gavialidae Category:Neogene crocodylomorpha Category:Prehistoric reptiles of South America